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31.
Paule Njiwa Clotilde Minfray Thierry Le Mogne Béatrice Vacher Jean-Michel Martin Shigeki Matsui Masaru Mishina 《Tribology Letters》2011,44(1):19-30
In this study, we are interested in the anti-wear properties of zinc dialkyl phosphate additive (ZP) in comparison with ‘classical’ zinc dialkyldithiophosphate (ZDDP). Friction tests were performed on a reciprocating tribometer using both ball-on-flat and cylinder-on-flat configurations
under a Hertzian contact pressure of 0.9 GPa. Experiments were carried out as a function of temperature (25 and 100 °C), sliding
speed (25, 50 and 100 mm/s) and additives concentrations. Ball wear scar diameters as well as friction coefficient were measured.
In order to better understand the anti-wear mechanisms of these additives, friction tests were followed by surface analyses
such as AES (Auger Electron Spectroscopy) and XPS (X-Ray Photoelectron Spectroscopy). Transmission Electron Microscopy (TEM)
observations of the ZDDP and ZP tribofilms were also carried out to visualise the generated layers. The anti-wear capability of ZP molecule is discussed. 相似文献
32.
Effects of club size in the provision of public goods. Network and congestion effects in the case of the French municipalities 总被引:2,自引:0,他引:2
The article formalizes and measures the impact of club size on the quality of the public good provided to its members. Under
a general framework we describe various functional forms that allow either network or crowding effects. Mechanisms of provision
are that of a political process in which both the demand and the supply sides are considered. Estimations use the whole set
of French municipalities. The supply model performs better than the demand model in the case of small municipalities, while
for large cities the demand model has higher explanatory power. In so far as impact of city size on the quality of club goods
is concerned, crowding does appear, but it does so in different patterns. For small towns marginal congestion first decreases
then increases with population. Marginal congestion is decreasing for cities of intermediate size. For larger cities no significant
effects are observed.
Received: 27 June 2000 / Accepted: 20 August 2001
RID="*"
ID="*" We have received particularly helpful comments from the editor-in-chief and two anonymous referees. We also thank Danièle
Moret-Bailly for her friendly computational assistance. 相似文献
33.
The peculiar behavior of thermoplastic elastomers in molding suggested that the processing steps (mainly shearing) to which the material had been submitted had a great influence on the morphology. Experiments were carried out on two polysstyrene-polybutadiene-polystyrene elastomers. The effects of melt-shearing and cooling were examined both by mechanical testing and low angle X-ray scattering. Melt-shearing creates a marked morphological anisotropy but a form of annealing can occur at sufficiently high temperatures. 相似文献
34.
35.
Smet C Leroy A Sillen A Wieruszeski JM Landrieu I Lippens G 《Chembiochem : a European journal of chemical biology》2004,5(12):1639-1646
A combined strategy to obtain a partial NMR assignment of the neuronal Tau protein is presented. Confronted with the extreme spectral degeneracy that the spectrum of this 441 amino acid long unstructured protein presents, we have introduced a graphical procedure based on residue type-specific product planes. Combining this strategy with the search for pairwise motifs, and combining the spectra of different Tau isoforms and even of peptides derived from the native sequence, we arrive at a partial assignment that is sufficient to map the interactions of Tau with its molecular partners. The obtained assignments equally confirm the absence of regular secondary structure in the isolated protein. 相似文献
36.
Evaporated 0.5 to 0.7 μm thick thin films of mNaFnAlF3 or mNafnCrF3 were prepared in a 1 mPa vacuum on glass substrates kept at room temperature. Chemical analysis and AC conductivity measurement revealed that in each case studied, a high ionic conductivity plateau existed for the composition range . The maximum conductivities at room temperature were σ = 1 × 10?6 S/mm for NaFAlF3 and σ = 2 × 10?5 S/m for NaFCrF3. Those high conductivities were discussed in terms of arrangement of MF6 octahedra. 相似文献
37.
Coated plutonia particle fuel has been proposed recently for use in radioisotope power systems and radioisotope heater units for a variety of space missions requiring power levels from milliwatts to tens or even hundreds of watts. The 238PuO2 fuel kernels are coated with a strong layer of ZrC designed to fully retain the helium gas generated by the radioactive decay of 238Pu. A recent investigation has concluded that helium retention in large-grain (200 μm) granular and polycrystalline fuel kernels is possible even at high-temperatures (>1700 K). Results of performance analysis showed that this fuel form could increase by 2.3–2.4 times the thermal power output of a light weight radioisotope heater unit. These figures are for a single-size (500 μm) particles compact, assuming 10% and 5% helium gas release respectively, and a fuel temperature of 1723 K, following 10 years of storage. A binary-size (300 and 1200 μm) particles compact increases the thermal power output of the RHU by an additional 15%. 相似文献
38.
In this paper, we consider dynamical graph-based models, which are well fitted for the structural analysis of complex systems. A significant amount of work has been devoted to the controllability of such graph based models, e.g. recently for multi-agent systems or complex networks. We study here the controllability through input addition in this framework. We present several variants of this problem depending on the freedom which is left to the designer on the additional inputs. We use a unified framework, which allows us to encompass the different applications and representations (large scale systems, complex communications networks, multi-agent systems, …) and provide convenient graph tools for their analysis. Our contribution is to characterize the structural modifications of the system resulting from an input addition (or a leader selection) and of the mechanisms which lead to controllability. We provide information on the possible location of additional inputs and on the minimal number of inputs to be added for controllability. 相似文献
39.
40.